The present invention relates to an information recording/reproducing apparatus having a high speed take-up mode in addition to a normal take-up mode, and more particularly to a take-up control device for a loaded tape cassette in the information recording/reproducing apparatus wherein a discrimination of a loaded tape cassette can be conducted by only one reel-cycle measurement circuit.
A recent type of take-up control device is provided with a high speed take-up mode in addition to a normal take-up mode in order to perform take up of the tape more speedy.
The high speed take-up mode is such a mode that a tape-up speed at a fast feeding time (FF time) and a rewinding time (REW time) can be varied in a plurality of steps according to a type of the tape cassette (i.e. a diameter of a reel hub). For example, a tape of 120 min can be wound up from the beginning to the end in about 1 minute.
There are a thick hub type of 62 mm and a thin hub type of 26 mm in diameter of the reel hub. Tapes of 30 min and 60 min are classified as the thick hub type, while tapes of 90 min and 120 min are classified as the thin hub type.
In the high speed take-up mode, the method of controlling the take-up speed varies depending on a difference between the diameters of the hubs (the thick hub type and the thin hub type). Therefore, it is necessary to discriminate the diameter of the reel hub, at a moment when the tape cassette is loaded in the apparatus and the first take-up mode is carried out.
Conventionally, the discrimination of the reel hub has been conducted on the basis of a calculated value A in the following calculation formula (1): EQU (4Tt).sup.2 +(4Ts).sup.2 =A(a constant value) (1)
In the formula, Tt is a reel pulse cycle of a take-up reel, and Ts is a reel pulse cycle of a supply reel.
In the above formula (1), each of the reel pulse cycles Tt and Ts is multiplied by 4. This is because 4 pulses of reel pulses are output on each one rotation of the reel. By multiplying each reel pulse by 4, a cycle of one rotation of the supply reel and a cycle of one rotation of the take-up reel can be obtained. Therefore, the formula (1) is a calculation formula for obtaining a sum of a square of the one rotation of the supply reel and a square of the one rotation of the take-up reel.
The value A is a proper value to be determined by the type of the tape cassette (the thick hub type and the thin hub type), and the tape cassette can be discriminated whether it is of the thick hub type or the thin hub type by means of the value A.
In the meantime, after the discrimination of the reel hub diameter is finished, a switching control of the tape speed in the take-up mode must be conducted in such a speed mode as corresponding to the discriminated reel hub diameter.
The switching of the tape speed in the take-up mode will be conducted by estimating an amount of the tape remaining in the supply reel (or the take-up reel). As one of methods for estimating the remaining amount of the tape, a ratio between the reel pulse cycle Ts of the supply reel and the reel pulse cycle Tt of the take-up reel (the following formulae (2) and (3)) is employed to determine a value N, and the tape speed will be changed by means of the value N. EQU N=Tt/Ts(FF mode) (2) EQU N=Ts/Tt(REW mode) (3)
As another method for estimating the remaining amount of the tape, as is disclosed in Japanese Patent Publication No. 58-27592B, number of remaining turns in the tape and remaining time can be calculated from a thickness of the tape, a diameter of the reel, reproduction speed of the tape and a rotation cycle of the reel.
As described, the related take-up control device is so constructed that the speed is controlled by estimating the remaining amount of the tape employing the reel pulse cycle Tt of the take-up reel and the reel pulse cycle Ts of the supply reel. The conventional device has a drawback that it requires a number of components and a complicated circuit structure, because two circuits are necessary for measuring the reel cycles respectively for the take-up reel and the supply reel.